Ezra Klein believes he has an answer. The does believe the scandals are significant, but:
The public is simply separating the scandals from Obama. They’re upset about the IRS, Benghazi, and DoJ stories. But most think the president has been truthful. Most think the IRS acted on its own. And the dissenters disapproved of Obama before the scandals, too.
The public’s reaction to the scandals is, in other words, being mediated by their reaction to Obama. If they approve of Obama, they’re inclined to believe that neither he nor anyone in his circle ordered the IRS to attack tea party groups and that the administration did its best in the immediate aftermath of Benghazi. If they disapprove of Obama, they’re inclined to believe he or someone in his circle was controlling the IRS, and that the Benghazi talking points were part of a cover-up.
“People respond along party lines,” writes Alan Abramowitz, an Emory political scientist who predicted last week that the polls would remain unchanged, “just like members of Congress. Republicans believe the worst of Obama, but they already believed the worst of Obama. Democrats (correctly) see Republicans pushing these things because they are out to get Obama and stop his agenda and/or they think Obama is responding correctly to the problems that do exist. So it’s like almost every other issue or controversy.”
The public is just as Congress is polarized along party lines. Each side made up their minds about the president long before the scandals emerged and each is exposing themselves to news that simply confirms their pre-exiting views.